Submarine groundwater discharge: An important source of new inorganic nitrogen to coral reef ecosystems

Using radium (Ra) isotopes and nutrient analyses, we found that submarine groundwater discharge (SGD) is an important source of "new" nutrients, particularly nitrogen, to coral reefs around the world. Nitrogen input estimates associated with SGD range from 3 to 800 mmol h^-1 per meter of shoreline. The use of Ra isotopes allows us to quantify the inorganic nitrogen input from this source of nutrients. Increasing coastal population and land use practices may enhance anthropogenic nutrient loading from submarine groundwater contributing to reef degradation.